powerpc/kdump: Use setjmp/longjmp to handle kdump and system reset recursion

[firefly-linux-kernel-4.4.55.git] / arch / powerpc / kernel / crash.c

diff --git a/arch/powerpc/kernel/crash.c b/arch/powerpc/kernel/crash.c
index 3d87b205d5f59bd815f4783082233ac9def8be5c..a8b6e2d705a46909163637eb9251829d0a7cc2a2 100644 (file)
--- a/arch/powerpc/kernel/crash.c
+++ b/arch/powerpc/kernel/crash.c
@@ -53,6 +53,16 @@ static cpumask_t cpus_in_crash = CPU_MASK_NONE;
 static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX+1];
 static DEFINE_SPINLOCK(crash_handlers_lock);
 
+static unsigned long crash_shutdown_buf[JMP_BUF_LEN];
+static int crash_shutdown_cpu = -1;
+
+static int handle_fault(struct pt_regs *regs)
+{
+       if (crash_shutdown_cpu == smp_processor_id())
+               longjmp(crash_shutdown_buf, 1);
+       return 0;
+}
+
 #ifdef CONFIG_SMP
 
 void crash_ipi_callback(struct pt_regs *regs)
@@ -89,14 +99,16 @@ void crash_ipi_callback(struct pt_regs *regs)
 static void crash_kexec_prepare_cpus(int cpu)
 {
        unsigned int msecs;
-
        unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
+       int tries = 0;
+       int (*old_handler)(struct pt_regs *regs);
 
        printk(KERN_EMERG "Sending IPI to other CPUs\n");
 
        crash_send_ipi(crash_ipi_callback);
        smp_wmb();
 
+again:
        /*
         * FIXME: Until we will have the way to stop other CPUs reliably,
         * the crash CPU will send an IPI and wait for other CPUs to
@@ -111,12 +123,52 @@ static void crash_kexec_prepare_cpus(int cpu)
 
        /* Would it be better to replace the trap vector here? */
 
-       if (cpumask_weight(&cpus_in_crash) < ncpus) {
-               printk(KERN_EMERG "ERROR: %d CPU(s) not responding\n",
-                       ncpus - cpumask_weight(&cpus_in_crash));
+       if (cpumask_weight(&cpus_in_crash) >= ncpus) {
+               printk(KERN_EMERG "IPI complete\n");
+               return;
+       }
+
+       printk(KERN_EMERG "ERROR: %d cpu(s) not responding\n",
+               ncpus - cpumask_weight(&cpus_in_crash));
+
+       /*
+        * If we have a panic timeout set then we can't wait indefinitely
+        * for someone to activate system reset. We also give up on the
+        * second time through if system reset fail to work.
+        */
+       if ((panic_timeout > 0) || (tries > 0))
+               return;
+
+       /*
+        * A system reset will cause all CPUs to take an 0x100 exception.
+        * The primary CPU returns here via setjmp, and the secondary
+        * CPUs reexecute the crash_kexec_secondary path.
+        */
+       old_handler = __debugger;
+       __debugger = handle_fault;
+       crash_shutdown_cpu = smp_processor_id();
+
+       if (setjmp(crash_shutdown_buf) == 0) {
+               printk(KERN_EMERG "Activate system reset (dumprestart) "
+                                 "to stop other cpu(s)\n");
+
+               /*
+                * A system reset will force all CPUs to execute the
+                * crash code again. We need to reset cpus_in_crash so we
+                * wait for everyone to do this.
+                */
+               cpus_in_crash = CPU_MASK_NONE;
+               smp_mb();
+
+               while (cpumask_weight(&cpus_in_crash) < ncpus)
+                       cpu_relax();
        }
 
-       printk(KERN_EMERG "IPI complete\n");
+       crash_shutdown_cpu = -1;
+       __debugger = old_handler;
+
+       tries++;
+       goto again;
 }
 
 /*
@@ -245,16 +297,6 @@ int crash_shutdown_unregister(crash_shutdown_t handler)
 }
 EXPORT_SYMBOL(crash_shutdown_unregister);
 
-static unsigned long crash_shutdown_buf[JMP_BUF_LEN];
-static int crash_shutdown_cpu = -1;
-
-static int handle_fault(struct pt_regs *regs)
-{
-       if (crash_shutdown_cpu == smp_processor_id())
-               longjmp(crash_shutdown_buf, 1);
-       return 0;
-}
-
 void default_machine_crash_shutdown(struct pt_regs *regs)
 {
        unsigned int i;